Here is the issue:I have the Pop Up connected and the fridge, overhead lights and 3 oulet inside the camper are dead. I checked the breakers and they are in the ON position. I reset a couple of times just in case.I checked the 15 and 20 amps(blue and yellow) fuses and they seem to be OK(not broken inside). Only one Outlet is working inside and that is where i connect the A/C and is working. Also working is the exterior light and the LP detector inside.So, half dead and the other half is working, any ideas???

that sounds like it is tripping for a reason. if u have anything plugged into the dead circuits, u may try unplugging them and see if it will reset.
if that doesn't work, it may be a bad ground fault. there is usually something wrong when they throw.
one other thought. u probably have several circuits in there but i would go to the outlet working (shut off the power to the trailer) then pull the outlet and see if there is another set of wires connecting to it. (they like to make the junctions there for other outlets. all the screws on the outlet are used when they do this). make sure those connections are made. may have to pull them all and check for tight wires to make sure they are all tight. they also like to push the wires in holes in the back of the outlet rather than use the side screws. pull gently on these wires and see they are making good contact (don't want them to come out).

if unplugging whatever is plugged into the circuit doesn't solve it. u will need to inspect the wiring runs for frays. most likely places will be where wires flex form something with AC supplied to it moves. ie if u have AC going to the top, look closely at the cable that ties between the top and the rest of the trailer.
it may take a little digging. had a contractor come to blow insulation at my home. when he plugged his work light in, the ground fault tripped. when i finally convinced him he had a problem with his light, he went in and one of the wires was touching the case.
is ur main power source also a ground fault? i've read (here) that ground faults don't like each other and that will cause one to trip.

to replace the gf outlet. purchase a replacement (most lumber yards or hardware stores). with the electricity unplugged from the trailer, pull the old outlet and move the wires to the same location on the new outlet.
ground fault outlets do go bad but i would look around first.
(with the power off) a final test would be to pull the outlet out and disconnect the wires leading away form it (should be labeled to somehow indicate gfi or out). reset the outlet. if u can safely put the power back to the trailer (without u, someone, or the trailer coming in contact with the exposed wire), do so and see if the outlet stays set. if it doesn't, good chance the outlet is bad and needs replacing.